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SubjectRe: [PATCHv3, RFC 00/34] Transparent huge page cache
Hi Kirill,
On 04/05/2013 07:59 PM, Kirill A. Shutemov wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> Here's third RFC. Thanks everybody for feedback.

Could you answer my questions in your version two?

>
> The patchset is pretty big already and I want to stop generate new
> features to keep it reviewable. Next I'll concentrate on benchmarking and
> tuning.
>
> Therefore some features will be outside initial transparent huge page
> cache implementation:
> - page collapsing;
> - migration;
> - tmpfs/shmem;
>
> There are few features which are not implemented and potentially can block
> upstreaming:
>
> 1. Currently we allocate 2M page even if we create only 1 byte file on
> ramfs. I don't think it's a problem by itself. With anon thp pages we also
> try to allocate huge pages whenever possible.
> The problem is that ramfs pages are unevictable and we can't just split
> and pushed them in swap as with anon thp. We (at some point) have to have
> mechanism to split last page of the file under memory pressure to reclaim
> some memory.
>
> 2. We don't have knobs for disabling transparent huge page cache per-mount
> or per-file. Should we have mount option and fadivse flags as part of
> initial implementation?
>
> Any thoughts?
>
> The patchset is also on git:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git thp/pagecache
>
> v3:
> - set RADIX_TREE_PRELOAD_NR to 512 only if we build with THP;
> - rewrite lru_add_page_tail() to address few bags;
> - memcg accounting;
> - represent file thp pages in meminfo and friends;
> - dump page order in filemap trace;
> - add missed flush_dcache_page() in zero_huge_user_segment;
> - random cleanups based on feedback.
> v2:
> - mmap();
> - fix add_to_page_cache_locked() and delete_from_page_cache();
> - introduce mapping_can_have_hugepages();
> - call split_huge_page() only for head page in filemap_fault();
> - wait_split_huge_page(): serialize over i_mmap_mutex too;
> - lru_add_page_tail: avoid PageUnevictable on active/inactive lru lists;
> - fix off-by-one in zero_huge_user_segment();
> - THP_WRITE_ALLOC/THP_WRITE_FAILED counters;
>
> Kirill A. Shutemov (34):
> mm: drop actor argument of do_generic_file_read()
> block: implement add_bdi_stat()
> mm: implement zero_huge_user_segment and friends
> radix-tree: implement preload for multiple contiguous elements
> memcg, thp: charge huge cache pages
> thp, mm: avoid PageUnevictable on active/inactive lru lists
> thp, mm: basic defines for transparent huge page cache
> thp, mm: introduce mapping_can_have_hugepages() predicate
> thp: represent file thp pages in meminfo and friends
> thp, mm: rewrite add_to_page_cache_locked() to support huge pages
> mm: trace filemap: dump page order
> thp, mm: rewrite delete_from_page_cache() to support huge pages
> thp, mm: trigger bug in replace_page_cache_page() on THP
> thp, mm: locking tail page is a bug
> thp, mm: handle tail pages in page_cache_get_speculative()
> thp, mm: add event counters for huge page alloc on write to a file
> thp, mm: implement grab_thp_write_begin()
> thp, mm: naive support of thp in generic read/write routines
> thp, libfs: initial support of thp in
> simple_read/write_begin/write_end
> thp: handle file pages in split_huge_page()
> thp: wait_split_huge_page(): serialize over i_mmap_mutex too
> thp, mm: truncate support for transparent huge page cache
> thp, mm: split huge page on mmap file page
> ramfs: enable transparent huge page cache
> x86-64, mm: proper alignment mappings with hugepages
> mm: add huge_fault() callback to vm_operations_struct
> thp: prepare zap_huge_pmd() to uncharge file pages
> thp: move maybe_pmd_mkwrite() out of mk_huge_pmd()
> thp, mm: basic huge_fault implementation for generic_file_vm_ops
> thp: extract fallback path from do_huge_pmd_anonymous_page() to a
> function
> thp: initial implementation of do_huge_linear_fault()
> thp: handle write-protect exception to file-backed huge pages
> thp: call __vma_adjust_trans_huge() for file-backed VMA
> thp: map file-backed huge pages on fault
>
> arch/x86/kernel/sys_x86_64.c | 12 +-
> drivers/base/node.c | 10 +
> fs/libfs.c | 48 +++-
> fs/proc/meminfo.c | 6 +
> fs/ramfs/inode.c | 6 +-
> include/linux/backing-dev.h | 10 +
> include/linux/huge_mm.h | 36 ++-
> include/linux/mm.h | 8 +
> include/linux/mmzone.h | 1 +
> include/linux/pagemap.h | 33 ++-
> include/linux/radix-tree.h | 11 +
> include/linux/vm_event_item.h | 2 +
> include/trace/events/filemap.h | 7 +-
> lib/radix-tree.c | 33 ++-
> mm/filemap.c | 298 ++++++++++++++++++++-----
> mm/huge_memory.c | 474 +++++++++++++++++++++++++++++++++-------
> mm/memcontrol.c | 2 -
> mm/memory.c | 41 +++-
> mm/mmap.c | 3 +
> mm/page_alloc.c | 7 +-
> mm/swap.c | 20 +-
> mm/truncate.c | 13 ++
> mm/vmstat.c | 2 +
> 23 files changed, 902 insertions(+), 181 deletions(-)
>



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